Use of certain 9-halo-13,14-dihydroprostaglandins to treat glaucoma and ocular hypertension

ABSTRACT

9-Halo-13,14-dihydroprostaglandins are useful in the treatment of glaucoma and ocular hypertension. Also disclosed are ophthalmic, pharmaceutical compositions comprising such prostaglandins.

BACKGROUND OF THE INVENTION

The present invention relates to the use of prostaglandins andprostaglandin analogues for the treatment of glaucoma and ocularhypertension. As used herein, the terms "prostaglandin" and "PG" shallrefer to prostaglandins and derivatives and analogues thereof, except asotherwise indicated by context.

Naturally-occurring prostaglandins, including prostaglandins of the Fseries (such as PGF₂α), the E series (such as PGE₂) and the D series(such as PGD₂), are known to lower intraocular pressure (IOP) aftertopical ocular instillation, but can cause marked conjunctival hyperemiaand/or inflammation with a number of associated side effects. There havebeen many attempts to synthesize prostaglandin derivatives which aremore effective at lowering IOP and/or which have reduced side effects.Such attempts have been made by Stjernschantz et al. (WO 90/02553) andWoodward (U.S. Pat. No. 5,093,329) to selectively reduce or eliminatethe side effects while maintaining the IOP-lowering effect.

SUMMARY OF THE INVENTION

It has now been unexpectedly discovered that certain9-halo-13,14-dihydroprostaglandins are significantly more effective inlowering IOP than other, known prostaglandins. In particular, thecompounds of the present invention have unexpectedly been found to lowerIOP between about 40 to 50%, with greatly reduced side effects,particularly with respect to hyperemia.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 graphically illustrates the results of the study presented inExample 4.

DETAILED DESCRIPTION OF THE INVENTION

The 9-halo-13,14-dihydroprostaglandins which are useful in thecompositions of the present invention have the general formula: ##STR1##wherein R₁ =CO₂ R₂, wherein R₂ =H, a cationic salt moiety, or anophthalmically acceptable ammonium moiety; or R₁ may also represent anophthalmically acceptable ester moiety;

X=halogen, particularly Cl or F, in either configuration;

Y=CH₂ or O;

R₃, R₄ can be the same or different, and are selected from: free orfunctionally modified hydroxy groups; and

n=0 or 1.

As used in this specification, the term "ophthalmically acceptable estermoiety" refers to an ophthalmically acceptable ester moiety whichhydrolyzes to the parent acid upon topical delivery to the eye. Examplesof ophthalmically acceptable esters include, but are not limited to: R₂=substituted or unsubstituted alkyl, cycloalkyl, (cycloalkyl)alkyl,aryl, arylalkyl, heteroaryl, or (heteroaryl)alkyl, wherein substituentsinclude alkyl, halo, a free or functionally modified hydroxy group, or afree or functionally modified thiol. As used in this specification, theterm "heteroaryl" refers to a monocyclic ring system of 5 or 6 atomscomposed of C, N, O, and/or S, such as furan, thiophene, pyrrole,pyrazole, imidazole, triazole, tetrazole, oxazole, isothiazole,thiazole, thiadiazole, pyridine, pyrimidine, pyradazine and pyrazine.Similarly, R₃ and R₄ represent either free hydroxy groups or acylated(esterified) hydroxy groups which hydrolyze to the parent hydroxy groupsupon topical delivery to the eye.

It is preferred to use compounds of formula (I) wherein: R₁ =CO₂ R₂ ; R₂=H, methyl, ethyl, n-propyl, isopropyl, t-butyl or benzyl; X=Cl in the β(R) configuration; Y=O or CH₂ ; R₃ and R₄ =OH; and n=1. It is mostpreferred to use compounds of formula (I) wherein: R₁ =CO₂ R₂ ; R₂ =H,methyl, ethyl, isopropyl or t-butyl; X=Cl in the β (R) configuration;Y=O; R₃ and R₄ =OH; and n=1.

Preferred compounds include: ##STR2##

The above-mentioned prostaglandins are disclosed in U.S. Pat. No.5,004,752 (Raduechel et al.) and EP 299 914 (Buchmann et al.). To theextent that U.S. Pat. No. 5,004,752 and EP 299 914 teach the preparationof the prostaglandins of the present invention, these patents are herebyincorporated by reference herein. The syntheses of some of theabove-mentioned prostaglandins are detailed below in Examples 1(Compound II), 2 (Compound III) and 3 (Compound IV).

In the examples below, the following standard abbreviations are used:g=grams (mg=milligrams); mol=moles (mmol=millimoles); mL=milliliters; mmHg=millimeters of mercury; mp=melting point; bp=boiling point; h=hours;and min=minutes. In addition, "NMR" refers to nuclear magnetic resonancespectroscopy and "CI MS" refers to chemical ionization massspectrometry. ##STR3##

EXAMPLE 1 Synthesis of Compound (II)

A: Dimethyl (2-cyclohexyl-2-oxo)ethylphosphonate (2):

A solution of dimethyl methylphosphonate (100 g, 0.8 mol) in 1.0 L ofanhydrous THF was cooled to -70° C. and n-BuLi (2.5M in hexanes, 320 mL,0.8 mol) was added dropwise such that the temperature remained below-60° C. The mixture was stirred for 10 min at -70° C. and then methylcyclohexanecarboxylate (57.3 mL, 0.4 mol) was added dropwise, viasyringe, over a period of 15 min. The resulting mixture was then stirredfor 14 h at room temperature. The reaction was quenched by first coolingto 0° C. followed by the addition of 2M HCl until the aqueous layer wasat pH 2. The layers were separated and the aqueous layer was extractedwith 2×200 mL of CH₂ Cl₂. The organic layers were combined and washedsequentially with 200 mL each of water and brine and then dried (MgSO₄).Filtration and solvent removal gave a yellow oil which was distilledunder vacuum to afford 67.3 g (72%) of 2 as a clear colorless liquid: bp100°-115° C. (0.01 mmHg); ¹ H NMR (CDCl₃) δ 3.74 (d, J=12.0 Hz, 6H),3.08 (d, J=22 Hz, 2H), 2.55 (m, 1H), 1.95-1.60 (m, 5H), 1.40-1.15 (m,5H).

B: (3aR, 4R, 5R, 6aS)-5-(Benzoyloxy)-4-(E)-3-cyclohexyl-3-oxo-1-propenyl!-hexahydro-2H-cyclopenta b!furan-2-one(4):

A solution of anhydrous THF (1.4 L), LiCl (11.7 g, 0.28 mol) and thephosphonate 2 (67.0 g, 0.28 mol) was cooled to 0° C. and triethylamine(39.2 mL, 0.28 mol) was added dropwise. A solution of the aldehyde 3(68.5 g, 0.25 mol) in dry CH₂ Cl₂ (320 mL) was added dropwise to thecold suspension and the resulting mixture was stirred at 0° C. for 3 h.The reaction mixture was then poured into 500 mL of 2M HCl, and layerswere separated. The aqueous layer was extracted with 500 mL of CH₂ Cl₂.Combined organic layers were washed with 100 mL each of water and brinefollowed by drying over MgSO₄. Filtration and solvent removal gave ayellow solid which was recrystallized from EtOAc to afford 85.8 g (89%)of 4 as a white solid: mp 151°-153° C.; ¹ H NMR (CDCl₃) δ 8.01 (d, J=2.0Hz, 2H), 7.65-7.40 (m, 3H), 6.70 (dd, J=12, 6 Hz, 1H), 6.35 (d, J=12 Hz,1H), 5.32 (m, 1H), 5.15 (m, 1H), 2.93 (m, 3H), 2.72-2.25 (m, 4H),1.85-1.56 (m, 6H), 1.40-1.15 (m, 5H).

C: (3aR, 4R, 5R, 6aS)-5-(Benzoyloxy)-4-(E)-(3S)-3-cyclohexyl-3-hydroxy-1-propenyl!-hexahydro-2H-cyclopentab!furan-2-one (5):

A solution of CeCl₃.7H₂ O (19.5 g, 52.3 mmol) and enone 4 (20.0 g, 52.3mmol) in 150 mL of CH₃ OH and 70 mL of CH₂ Cl₂ was prepared. NaBH₄ (1.92g, 52.3 mmol) was added in small portions over a period of 5 min. Theresulting mixture was stirred at ambient temperature for 45 min and thenwas poured into a separatory funnel containing 100 mL each of 25% (v/v)aqueous acetic acid and CH₂ Cl₂. Layers were separated and the aqueouslayer was extracted with 3×50 mL of CH₂ Cl₂. Combined organic layerswere washed with sat. NaHCO₃ (50 mL), and brine (50 mL), and then dried(MgSO₄). Upon solvent removal, 23.7 g of a colorless oil containingnearly equal amounts of the two diastereomeric allyl alcohols wasobtained. Diastereomers were separated by HPLC (40% EtOAc/hexane),affording 5 (9.34 g (46%), the less polar component) as a white solid. ¹H NMR (CDCl₃) δ 8.01 (d, J=8 Hz, 2H), 7.62-7.28 (m, 3H), 5.61 (m, 2H),5.25 (m, 1H), 5.08 (m, 1H), 3.85 (m, 1H), 2.95-2.45 (m, 5H), 2.30 (m,2H), 1.95-1.55 (m, 6H), 1.50-0.80 (m, 5H).

D: (3aR, 4R, 5R, 6aS)-4-(3R)-3-Cyclohexyl-3-hydroxypropyl!-hexahydro-5-hydroxy-2H-cyclopentab!furan-2-one (7):

A solution of the allyl alcohol 5 (10.0 g, 26.0 mmol) in warm methanol(100 mL) was cooled to ambient temperature. Anhydrous K₂ CO₃ (3.6 g,26.0 mmol) was added and the resulting mixture was stirred at ambienttemperature for 3 h. The reaction mixture was concentrated and theresidue was partitioned between 100 mL each of EtOAc and 1M HCl. Layerswere separated and the aqueous phase was extracted with 3×50 mL ofEtOAc. Combined organic layers were washed with 50 mL of water, 2×50 mLof sat. NaHCO₃, 50 mL of brine, and dried over MgSO₄. Filtration andevaporation gave the diol 6 (9.8 g, 92% yield, R_(f) 0.26, 100% EtOAc),which was used in the subsequent reaction without further purification.

The crude diol 6 (9.8 g, 26 mmol) was dissolved in 50 mL of EtOAc and acatalytic amount (0.1 g) of 5% Pd/C was added. This mixture washydrogenated at 30-40 psi in a Parr hydrogenation apparatus for 3 h andthen filtered through a short pad of Celite. The filtrate wasconcentrated and the crude yellow oil was purified by passage through ashort column of silica (R_(f) 0.26, EtOAc) to afford 7 (5.06 g, 70%yield from 5) as a colorless, viscous oil which solidified uponstanding. ¹ H NMR (CDCl₃) δ 4.95 (m, 1H), 4.05 (m, 1H), 3.35 (m, 1H),2.80 (m, 1H), 2.58 (m, 2H), 2.30 (m, 1H), 2.00 (m, 14H).

E: (3aR, 4R, 5R, 6aS)-4-(3R)-3-Cyclohexyl-3-(tetrahydropyran-2-yloxy)propyl!-hexahydro-5-(tetrahydropyran-2-yloxy)-2H-cyclopentab!furan-2-one (8):

A solution of the diol 7 (6.0 g, 21.2 mmol) and dihydropyran (7.80 mL,84.8 mmol) in CH₂ Cl₂ (100 mL) was cooled to 0° C. A catalytic amount ofp-TsOH (0.05 g, 0.26 mmol) was added and the mixture was stirred for 30min at 0° C. The reaction was then quenched by adding sat. aqueousNaHCO₃ (10 mL). Layers were separated and the aqueous phase wasextracted with 2×25 mL of CH₂ Cl₂. Combined organic layers were driedover anhydrous K₂ CO₃, filtered and concentrated to afford a colorlessoil which was purified by passage through a short column of silica(R_(f) 0.46, 1:1 EtOAc/hexanes). The bis-THP ether 8 (8.59 g, 89% yield)was isolated as a colorless oil which solidified upon standing. ¹ H NMR(CDCl₃) δ (characteristic peaks only) 5.00 (m, 1H), 4.75-4.45 (m, 2H),3.85 (m, 2H), 3.60-3.30 (m, 4H).

F: (9S, 11R,15R)-11,15-Bis-(tetrahydropyran-2-yloxy)-15-cyclohexyl-2,3,4,5,6,16,17,18,19,20-decanor-9-(triethylsilyloxy)prostanolTriethylsilyl Ether (10):

A suspension of lithium aluminum hydride (1.43 g, 38.0 mmol) in 50 mL ofanhydrous THF was cooled to 0° C. and a solution of the lactone 8 (8.59g, 19.0 mmol) in THF (100 mL) was added dropwise. The resulting mixturewas stirred at 0° C. for 3 h after which 1.5 mL of H₂ O, 1.5 mL 15% NaOHand 4.5 mL of H₂ O were sequentially added. After warming to ambienttemperature, 100 mL of EtOAc was added and solids were filtered off. Thefilter cake was washed thoroughly with 3×50 mL of EtOAc and thefiltrates were dried by passage through a short pad anhydrous MgSO₄.Evaporation afforded 9 (9.02 g) as a colorless oil which was used in thesubsequent step without further purification (R_(f) 0.31, 80:20EtOAc/hexanes).

A mixture of the crude diol 9 (9.02 g, 19.0 mmol), triethylsilylchloride (9.65 mL, 57.0 mmol), dimethylaminopyridine (0.41 g, 3.42mmol), triethylamine (16.0 mL, 114 mmol) and anhydrousN,N-dimethylformamide (50 mL) was stirred at ambient temperature for 14h under N₂. The reaction mixture was then diluted with 250 mL of CH₂ Cl₂and the solution was washed with 3×50 mL H₂ O. Combined water washeswere extracted with 2×50 mL of CH₂ Cl₂. Organic layers were combined,dried (MgSO₄), filtered and concentrated to afford a yellow oil whichwas chromatographed on silica (R_(f) 0.4, 1:9 EtOAc/hexanes). Pure 10(11.23 g, 86% yield from 8) was obtained as a slightly yellow oil. ¹ HNMR (CDCl₃) δ (characteristic peaks only) 4.62 (m, 2H), 4.15-3.25 (broadm, 7H), 2.30-1.15 (broad m, 18H), 0.95 (broad t, 18H), 0.65 (broad q,12H).

G: (9S, 11R,15R)-11,15-Bis-(tetrahydropyran-2-yloxy)-15-cyclohexyl-2,3,4,5,6,16,17,18,19,20-decanor-9-(triethylsilyloxy)prostanal(11):

A solution of oxalyl chloride (0.51 mL, 0.57 mmol) in anhydrous CH₂ Cl₂(15 mL) was cooled to -78° C. under N₂. A solution of anhydrous DMSO(0.81 mL, 11.4 mmol) in CH₂ Cl₂ (2.0 mL) was then added dropwise. After2 min, a solution of 10 (2.6 g, 3.8 mmol) in 8 mL of dry CH₂ Cl₂ wasintroduced dropwise via syringe over a period of 2 min. The resultingmixture was stirred at -78° C. for 2 h at which time triethylamine (2.7mL, 19.0 mmol) was added. The reaction was stirred for 15 min and thenallowed to warm to ambient temperature. The mixture was partitionedbetween 100 mL of EtOAc and 10 mL of H₂ O and the organic layer waswashed with an additional 10 mL H₂ O, 10 mL of brine and dried (MgSO₄).Solvent removal gave a yellow oil which was subjected to chromatographyon silica gel (R_(f) 0.2, 10% EtOAc/hexanes) to afford 11 (1.4 g, 65%yield) and some starting material (0.83 g). ¹ H NMR (CDCl₃) δ 9.80(broad s, 1H), 4.62 (m, 2H), 4.20 (m, 1H), 3.85-3.60 (m, 3H), 3.40 (m,3H), 2.80 (m, 1H), 2.45-2.05 (m, 4H), 1.95-1.10 (broad m, 27H), 0.95(broad t, 9H), 0.55 (broad q, 6H).

H: (5Z)-(9S, 11R,15R)-11,15-Bis-(tetrahydropyran-2-yloxy)-15-cyclohexyl-2,3,4,16,17,18,19,20-octanor-9-(triethylsilyloxy)-5-prostenoicAcid Methyl Ester (12):

A solution of 18-crown-6 (8.50 g, 32.1 mmol) andbis(2,2,2-trifluoroethyl) (methoxycarbonylmethyl)phosphonate (3.72 g,11.7 mmol) in 110 mL of THF was cooled to -78° C. KHMDS (0.5M intoluene, 23.4 mL, 11.7 mmol) was added to the above mixture and thesolution was stirred for 15 min. Aldehyde 11 (6.11 g, 10.7 mmol) in 5.0mL of THF was added dropwise over a period of 15 min. The reaction wasstirred at -78° C. for 2 h, then warmed up to 0° C. and stirred at thattemperature for 2 more hours. The reaction was quenched by adding 50 mLof saturated aqueous NH₄ Cl and the mixture was allowed to warm to roomtemperature. Layers were separated and the aqueous layer was extractedwith 2×50 mL of EtOAc. Combined organic layers were washed with 2×50 mLof brine and dried (K₂ CO₃). Filtration and solvent removal gave a crudeyellow oil which was purified by passage through a short plug of silicato afford a mixture of 12 and its E isomer (9:1 ratio, 6.28 g, 95%yield). Isomers were separated by chromatography on silica gel (R_(f)0.56, and 0.47, for the major and minor isomers respectively, 40% Et₂O/hexane); 4.57 g of pure 12 and 0.97 g of a 1:1 E/Z mixture wereisolated. ¹ H NMR (CDCl₃) δ 6.35 (m, 1H), 5.78 (broad d, J=12.0 Hz, 1H),4.65 (m, 2H), 4.28 (m, 1H), 3.90 (m, 2H), 3.70 (s, 3H), 3.55-3.30 (m,3H), 2.80 (m, 2H), 2.35-2.05 (m, 1H), 2.00-1.10 (broad m, 30H), 0.95(broad t, 9H), 0.60 (broad q, 6H).

I: (5Z)-(9S, 11R,15R)-11,15-Bis-(tetrahydropyran-2-yloxy)-15-cyclohexyl-2,3,4,16,17,18,19,20-octanor-9-(triethylsilyloxy)-5-prosten-1-ol(13):

A solution of 12 (2.0 g, 3.22 mmol) in 20 mL of anhydrous THF was cooledto 0° C. under N₂. A solution of diisobutylaluminum hydride (1.5M intoluene, 6.5 mL, 9.66 mmol) was added dropwise and the resulting mixturewas stirred at 0° C. for 2 h. The reaction was then quenched by carefuladdition of CH₃ OH (5 mL), allowed to warm up to ambient temperature,and diluted with 50 mL of THF. The resulting cloudy solution was treatedwith 50 mL of a saturated aqueous solution of sodium potassium tartrateand the biphasic mixture was stirred for 1 h. Layers were then separatedand the aqueous layer was extracted with 2×50 mL of THF. Organicextracts were combined, washed with brine (50 mL), and dried (MgSO₄).Filtration and solvent removal gave a pale yellow oil which was purifiedby chromatography on silica gel (R_(f) 0.26, 4:6 Et₂ O/hexane) to yield13 (1.95 g, 95% yield) as a colorless oil. This compound was usedimmediately in the subsequent reaction. ¹ H NMR (CDCl₃) δ 5.65 (m, 2H),4.65 (m, 2H), 4.30-3.25 (broad m, 5H), 2.40-2.05 (broad m, 4H),2.00-1.10 (broad m, 32H), 1.00 (broad t, 9H), 0.60 (broad q, 6H).

J: (5Z)-(9S, 11R,15R)-11,15-Bis-(tetrahydropyran-2-yloxy)-15-cyclohexyl-9-hydroxy-3-oxa-16,17,18,19,20-pentanor-5-prostenoicAcid t-Butyl Ester (15):

A mixture of 13 (1.95 g, 3.28 mmol), t-butyl bromoacetate (5.11 g, 26.24mmol), tetrabutylammonium hydrogen sulfate (0.8 g, 2.35 mmol), toluene(45 mL) and 25% (wt/wt) aqueous NaOH (30 mL) was stirred vigorously atroom temperature for 18 h. Layers were separated and the aqueous layerwas extracted with 2×25 mL of EtOAc. Combined organic extracts werewashed with brine (15 mL), dried (MgSO₄), and concentrated. Crudeproduct was purified by chromatography on silica gel (R_(f) 0.56, 20%EtOAc/hexane) to yield 2.19 g of 14 (contaminated with some t-butylbromoacetate) and 0.48 g of the starting allyl alcohol 13. The allylether 14 thus obtained was used in the desilylation reaction withoutfurther purification.

The silyl ether 14 (0.5 g) obtained above was dissolved in 3.0 mL ofDMSO and to it was added 2.2 mL of tetrabutylammonium fluoride (1.0M inTHF, 2.2 mmol). The mixture was stirred at ambient temperature for 30min and then partitioned between 50 mL EtOAc and 10 mL brine. Theaqueous layer was extracted with 2×10 mL of EtOAc and the combinedorganic extracts were dried over MgSO₄. Evaporation and chromatographyon silica gel (R_(f) 0.44, 50% EtOAc/hexane) afforded 0.28 g of 15 as acolorless oil. ¹ H NMR (CDCl₃) δ 5.65 (m, 2H), 4.62 (m, 2H), 4.16 (m,1H), 4.10-3.75 (m, 3H), 3.95 (s, 2H), 3.45 (m, 2H), 2.50-0.90 (broad m,35H), 1.46 (s, 9H); High Resolution CI MS m/z (CI) calcd for C₃₄ H₅₉ O₈(MH⁺) 595.4209, found 595.4208.

K: (5Z)-(9R, 11R,15R)-9-Chloro-15-cyclohexyl-11,15-dihydroxy-3-oxa-16,17,18,19,20-pentanor-5-prostenoicAcid t-Butyl Ester (Compound (II)):

The hydroxyester 15 (0.28 g, 0.47 mmol) was dissolved in 4.0 mL of astock solution containing 48.0 mL of CH₃ CN, 0.79 mL of pyridine, and0.97 mL of CCl₄. Triphenylphosphine (0.18 g, 0.70 mmol) was added andthe resulting mixture was stirred at ambient temperature for 17 h. Thereaction mixture was treated with 10 mL of a 1:1 solution of Et₂O/hexanes and the precipitate formed was filtered off. The filtrate wasconcentrated and purified by chromatography (silica gel, R_(f) 0.47,40:60 Et₂ O/hexanes) to yield pure 16 (90 mg, 34%) as a colorless oil.

A solution of 16 (80 mg, 0.13 mmol) in 7.0 mL of 65% (v/v) aqueousacetic acid was heated to 65°-70° C. for 45 min. The reaction mixturewas cooled to room temperature and concentrated. The resulting residuewas redissolved in anhydrous EtOH and the solvent was again evaporated.The residue thus obtained was purified by chromatography on silica gel(R_(f) 0.4, 60:40 EtOAc/hexanes) to yield 60 mg (100%) of Compound (II)as a colorless, viscous oil. ¹ H NMR (CDCl₃) δ 5.69 (m, 2H), 4.32-3.85(m, 5H), 3.38 (m, 1H), 2.50-1.95 (m, 5H), 1.95-0.80 (broad m, 29H) 1.43(s, 9H); ¹³ C NMR (CDCl₃) δ 169.9, 131.7, 126.8, 82.0, 75.6, 75.1, 67.9,66.6, 54.2, 51.0, 44.3, 43.7, 31.4, 30.3, 30.1, 29.3, 28.1, 28.0, 26.5,26.3, 26.1; High Resolution CI MS m/z calcd for C₂₄ H₄₂ O₅ Cl (MH⁺)445.2720, found 445.2716. ##STR4##

EXAMPLE 2 Synthesis of Compound (III)

A: (5Z)-(9S, 11R,15R)-11,15-Bis-(tetrahydropyran-2-yloxy)-15-cyclohexyl-9-hydroxy-3-oxa-16,17,18,19,20-pentanor-5-prostenoicAcid (17):

Hydroxyester 15 (0.454 g; 0.76 mmol; see Example 1) was dissolved in 10mL of methanol and 2 mL of water. Lithium hydroxide monohydrate (0.16 g;500 mol %) was added and the mixture was stirred at room temperature.After 18 h, 20 mL of saturated, aqueous KH₂ PO₄ and 20 mL CH₂ Cl₂ wereadded, layers were separated, and the aqueous phase was washed withadditional CH₂ Cl₂ (3×20 mL). Combined organic layers were dried overNa₂ SO₄, filtered, and concentrated, affording 0.47 g of a colorless oilwhich was used directly in the next reaction.

B: (5Z)-(9S, 11R,15R)-11,15-Bis-(tetrahydropyran-2-yloxy)-15-cyclohexyl-9-hydroxy-3-oxa-16,17,18,19,20-pentanor-5-prostenoicAcid Isopropyl Ester (18):

Crude acid 17 from above (0.23 g; 0.43 mmol) was dissolved in 10 mL ofacetone. DBU (0.25 mL; 400 mol %) and isopropyl iodide (0.21 g; 300 mol%) were added and the mixture was stirred for 12 h at room temperature.After evaporation, the residue was applied to a silica gel column andeluted with hexane/EtOAc, 1/1, to afford 0.157 g (63%) of isopropylester 18 as a colorless oil. R_(f) =0.49; ¹ H NMR (CDCl₃) δ(characteristic peaks only) 5.80-5.52 (m, 2H), 5.15 (sep, 1H, J=6.2 Hz),4.03 (broad s, 2H), 1.27 (d, 6H, J=6.2 Hz).

C: (5Z)-(9R, 11R,15R)-9-Chloro-15-cyclohexyl-11,15-dihydroxy-3-oxa-16,17,18,19,20-pentanor-5-prostenoicAcid Isopropyl Ester (Compound III):

The hydroxyester 18 (0.146 g; 0.25 mmol) was dissolved in 3.0 mL of astock solution containing 48 mL of CH₃ CN, 0.79 mL of pyridine, and 0.97mL of CCl₄. Triphenylphosphine (0.10 g; 150 mol %) was added and theresulting mixture was stirred at room temperature for 17 h. The reactionmixture was treated with 10 mL of a 1:1 solution of Et₂ O/hexanes andthe precipitate was filtered off. The filtrate was concentrated andchromatographed on silica gel (hexane/EtOAc, 4/1), affording 0.108 g ofa colorless oil which consisted of a nearly equimolar mixture of desiredchlorinated material 19 with its undesired 5,8-diene eliminationproduct.

A solution of crude 19 from above in 10 mL of 65% (v/v) aqueous aceticacid was warmed to 65° C. for 45 min. The mixture was then cooled toroom temperature and concentrated. The resulting residue was thenpurified by silica gel chromatography (hexane/EtOAc, 2/3), affording 27mg (25% based on 18) of pure Compound (III) (R_(f) =0.56) as a colorlessoil with 69 mg of a mixture of Compound (III) and its 5,8-dieneelimination product (R_(f) =0.45). ¹ H NMR (CDCl₃) δ 5.67 (m, 2H), 5.08(sep, 1H, J=6.1), 4.30-3.95 (m, 6H), 3.40 (m, 1H), 2.35 (m, 2H),2.30-2.00 (m, 3H), 1.93-1.35 (m, 12H), 1.25 (d, 6H, J=6.2 Hz), 1.22-0.90(m, 6H); ¹³ C NMR (CDCl₃) δ 170.2, 131.8, 126.7, 75.7, 75.2, 68.8, 67.6,66.7, 61.2, 54.2, 51.1, 44.4, 43.6, 31.4, 30.2, 30.1, 29.3, 28.0, 26.5,26.3, 26.1, 21.8; High Resolution CI MS m/z calcd for C₂₃ H₄₀ O₅ Cl(MH⁺) 431.2564, found 431.2569. ##STR5##

EXAMPLE 3 Synthesis of Compound (IV)

A: (5Z)-(9S, 11R,15R)-11,15-Bis-(tetrahydropyran-2-yloxy)-15-cyclohexyl-9-hydroxy-16,17,18,19,20-pentanor-5-prostenoicAcid Isopropyl Ester (22):

To a solution of 5.0 g (11 mmol) of lactone 8 (see Example 1) in 40 mLof THF at -78° C. was added dropwise 9.6 mL (14.4 mmol) of a 1.5Msolution of diisobutylaluminum hydride in toluene. After 1.5 h, 5 mL ofMeOH was added, the mixture was stirred for 10 min at -78° C. and thenwarmed to room temperature. This solution was then added to a mixture of20 mL of saturated, aqueous NH₄ Cl, 35 mL of EtOAc, and 35 mL ofsaturated, aqueous sodium potassium tartrate. The mixture was stirredfor 20 min, layers were separated, and the aqueous layer was washed withEtOAc (3×40 mL). Combined organic layers were dried over MgSO₄,filtered, and evaporated. The resulting residue was purified by silicagel chromatography (EtOAc/hexane, 1/1), affording 4.5 g (90%) of lactol20 which was used directly in the next reaction.

To a solution of 14.1 g (31.8 mmol) of(1-carboxypent-5-yl)triphenylphosphonium bromide in 100 mL of THF at 0°C. was added dropwise 59 mL (59 mmol) of a 1M solution of potassiumt-butoxide in THF. After 20 min, 4.5 g (9.9 mmol) of lactol 17 in 20 mLof THF was added dropwise. The reaction was quenched after 2 h bypouring into 150 mL of a 1/1 (v/v) mixture of EtOAc/saturated, aqueousNH₄ Cl. Layers were separated and the aqueous layer was extracted withEtOAc (3×70 mL). Combined organic layers were dried over MgSO₄, filteredand evaporated, leaving 7.6 g of crude acid 21 as an oil.

Crude acid 21 (7.6 g) was dissolved in 55 mL of acetone, cooled to 0°C., and 8.6 g (56 mmol) of DBU was added dropwise. The reaction waswarmed to room temperature and 8.5 g (50 mmol) of isopropyl iodide wasadded dropwise. After stirring for 14 h, the mixture was poured into 100mL of a 1/1 (v/v) mixture of EtOAc/saturated, aqueous NH₄ Cl. Layerswere separated and the aqueous phase was extracted with additional EtOAc(2×100 mL). Combined organic layers were dried over MgSO₄, filtered,evaporated, and chromatographed on silica gel (EtOAc/hexane, 2/3)affording 1.98 g (35% from lactol 20) of 22. ¹ H NMR (CDCl₃) δ(characteristic peaks only) 5.58-5.28 (m, 2H), 4.97 (sep, J=6.2 Hz, 1H),1.1 (d, J=6.2 Hz, 6H).

B: (5Z)-(9R, 11R,15R)-9-Chloro-15-cyclohexyl-11,15-dihydroxy-16,17,18,19,20-pentanor-5-prostenoicAcid Isopropyl Ester (Compound IV):

Hydroxyester 22 (513.1 mg; 0.8864 mmol) was dissolved in 6.6 mL of astock solution containing 48.0 mL of CH₃ CN, 0.79 mL of pyridine, and0.97 mL of CCl₄. Triphenylphosphine (348.8 mg; 150 mol %) was added andthe mixture was stirred for 45 h at room temperature. The reaction wasthen diluted with 7 mL of Et₂ O and 14 mL of hexane. After stirring for10 min, solids were filtered off and the filtrate was evaporated. Theresulting solids were triturated three times with 15 mL of hexane/Et₂ O(1/2). Combined hexane/Et₂ O washes were concentrated down to 0.75 g ofa white solid which was then redissolved in hexane/Et₂ O andchromatographed on silica gel. Elution with hexane/Et₂ O, 5/1, afforded372.8 mg of semipure 23 which was used directly in the next reaction.

Crude 23 from above was dissolved in 20 mL of 65% (v/v) aqueous HOAc andwarmed to room temperature. After 1.5 h, the reaction was concentrated,15 mL of H₂ O was added, and the solution was reconcentrated. AbsoluteEtOH (15 mL) was added followed, again, by reconcentration. Theresulting oil was purified by silica gel chromatography (hexane/EtOAc,2/1), affording 244.1 mg of a mixture of Compound (IV) contaminated withan approximately equal quantity of the 5,8-diene side product. An 8.2 mgsample was then further purified by reverse phase HPLC, giving 4.4 mg ofpure Compound (IV) as a clear, viscous oil. ¹ H NMR (CDCl₃) δ 5.47 (m,J=8.5 Hz, 2H), 5.01 (sep, J=6.3 Hz, 1H), 4.10 (dt, J=4.0, 6.2 Hz, 1H),4.04 (q, J=7.6 Hz, 1H), 3.37 (m, 1H), 2.35-2.24 (m, 4H), 2.20-2.07 (m, 4H), 1.82 (br s, 2H), 1.80-1.50 (m, 13H), 1.36-0.96 (m, 12H). ¹³ C NMR(CDCl₃) δ 173.2, 131.0, 126.8, 76.2, 76.0, 67.5, 60.8, 54.3, 51.7, 44.5,43.5, 34.0, 31.7, 30.0, 29.2 (two overlapping resonances), 27.9, 26.6,26.4, 26.2, 26.1, 24.9, 21.8. High Resolution CI MS m/z calcd for C₂₄H₄₂ O₄ Cl (MH⁺) 429.2772, found 429.2763.

The compounds of formula (I) are useful in lowering intraocular pressureand thus are useful in the treatment of glaucoma. The preferred route ofadministration is topical. The dosage range for topical administrationis generally between about 0.001 and about 1000 micrograms per eye(μg/eye) and is preferably between about 0.01 and about 100 μg/eye andmost preferably between about 0.05 and about 50 μg/eye. The compounds ofthe present invention can be administered as solutions, suspensions, oremulsions (dispersions) in a suitable ophthalmic vehicle.

In forming compositions for topical administration, the compounds of thepresent invention are generally formulated as between about 0.0001 toabout 0.5 percent by weight (wt %) solutions in water at a pH betweenabout 4.5 and about 8.0. It is preferable to use concentrations betweenabout 0.0005 to about 0.1 wt % and, most preferably, between about 0.001and about 0.1 wt %. While the precise regimen is left to the discretionof the clinician, it is recommended that the resulting solution betopically applied by placing one drop in each eye one or two times aday.

Other ingredients which may be desirable to use in the ophthalmicpreparations of the present invention include preservatives, co-solventsand viscosity building agents.

Antimicrobial Preservatives:

Ophthalmic products are typically packaged in multidose form, whichgenerally require the addition of preservatives to prevent microbialcontamination during use. Suitable preservatives include: benzalkoniumchloride, thimerosal, chlorobutanol, methyl paraben, propyl paraben,phenylethyl alcohol, edetate disodium, sorbic acid, ONAMER M®, or otheragents known to those skilled in the art. Such preservatives aretypically employed at a concentration between about 0.001 and about 1.0wt %.

Co-Solvents:

Prostaglandins, and particularly ester derivatives, typically havelimited solubility in water and therefore may require a surfactant orother appropriate co-solvent in the composition. Such co-solventsinclude: Polysorbate 20, 60 and 80; Pluronic F-68, F-84 and P-103;Tyloxapol; Cremophor EL, sodium dodecyl sulfate; glycerol; PEG 400;propylene glycol; cyclodextrins; or other agents known to those skilledin the art. Such co-solvents are typically employed at a concentrationbetween about 0.01 and about 2 wt %.

Viscosity Agents:

Viscosity greater than that of simple aqueous solutions may be desirableto increase ocular absorption of the active compound, to decreasevariability in dispensing the formulations, to decrease physicalseparation of components of a suspension or emulsion of formulationand/or otherwise to improve the ophthalmic formulation. Such viscositybuilding agents include: polyvinyl alcohol; polyvinyl pyrrolidone;cellulosic polymers, such as methyl cellulose, hydroxy propylmethylcellulose, hydroxyethyl cellulose, carboxymethyl cellulose,hydroxy propyl cellulose; carboxy vinyl polymers, such as carbomer 910,carbomer 940, carbomer 934P and carbomer 1342; or other agents known tothose skilled in the art. Such agents are typically used at aconcentration between about 0.01 and about 2 wt %.

EXAMPLE 4

The following Formulations A-D are representative pharmaceuticalcompositions of the invention for topical use in lowering of intraocularpressure. Each of Formulations A-D may be formulated in accordance withprocedures known to those skilled in the art.

    ______________________________________                                        Ingredient              Amount (wt %)                                         ______________________________________                                        Formulation A:                                                                Compound (II)           0.01                                                  Monobasic sodium phosphate                                                                            0.05                                                  Dibasic sodium phosphate                                                                              0.15                                                  (anhydrous)                                                                   Sodium chloride         0.75                                                  Disodium EDTA (Edetate disodium)                                                                      0.01                                                  Benzalkonium chloride   0.02                                                  Polysorbate 80          0.5                                                   HCl and/or NaOH         pH 7.3-7.4                                            Purified water          q.s. to 100%                                          Formulation B:                                                                Compound (III)          0.01                                                  Monobasic sodium phosphate                                                                            0.05                                                  Dibasic sodium phosphate                                                                              0.15                                                  (anhydrous)                                                                   Sodium chloride         0.75                                                  Disodium EDTA (Edetate disodium)                                                                      0.05                                                  Cremophor EL            0.1                                                   Benzalkonium chloride   0.01                                                  HCl and/or NaOH         pH 7.3-7.4                                            Purified water          q.s. to 100%                                          Formulation C:                                                                Formula (I), wherein: R.sub.1 = CO.sub.2 R.sub.2,                                                     0.1                                                   R.sub.2 = H, X = β(R)Cl, Y = O, R.sub.3 = R.sub.4 = OH,                  and n = 1                                                                     Monobasic sodium phosphate                                                                            0.05                                                  Dibasic sodium phosphate                                                                              0.15                                                  (anhydrous)                                                                   Sodium chloride         0.5                                                   Hydroxypropyl-β-cyclodextrin                                                                     4.0                                                   Benzalkonium chloride   0.01                                                  NaOH and/or HCl         pH 6.3-6.6                                            Purified water          q.s. to 100%                                          Formulation D:                                                                Formula (I), wherein: R.sub.1 = CO.sub.2 R.sub.2,                                                     0.2                                                   R.sub.2 = H, X = β(R)Cl, Y = CH.sub.2, R.sub.3 = R.sub.4 = OH,           and n = 0                                                                     Monobasic sodium phosphate                                                                            0.05                                                  Dibasic sodium phosphate                                                                              0.15                                                  (anhydrous)                                                                   Sodium chloride         0.6                                                   Tyloxapol               0.5                                                   Benzalkonium chloride   0.02                                                  NaOH and/or HCl         pH 6.3-6.6                                            Purified water          q.s. to 100%                                          ______________________________________                                    

EXAMPLE 5

The ability of certain compounds of the present invention to reduceintraocular pressure (IOP) was evaluated in cynomolgus monkeys withocular hypertension produced by previous laser trabeculoplasty in theright eye. Animals had been trained to sit in restraint chairs andconditioned to accept experimental procedures without chemicalrestraint. IOP was determined with a pneumatonometer after light cornealanesthesia with dilute proparacaine. The test protocol included atreatment regimen consisting of 5 divided doses administered over aperiod of 2 and 1/2 days. Doses 2-5 were given 8, 24, 32 and 48 hoursafter the initial dose. Baseline IOP values were determined prior totreatment with the test formulation, and then IOP was determined 16hours after the fourth dose, and 2, 4 and 6 hours after the fifth dose.Prostaglandin doses are micrograms of compound contained in eachtreatment.

The two compounds tested are those previously identified as Compounds(II) and (IV).

                                      TABLE 1                                     __________________________________________________________________________               Baseline                                                                            Percent IOP Reduction at Hours after                                PG  IOP   Dose/Dose#                                                   Compound                                                                             Dose                                                                              (mm Hg)                                                                             16/4 2/5   4/5  6/5                                          __________________________________________________________________________    (II)   5 μg                                                                           36.3  38.3 ± 3.0                                                                      47.5 ± 5.1                                                                       43.7 ± 5.6                                                                      36.5 ± 5.8                                (II)   1 μg                                                                           36.9  22.3 ± 2.7                                                                      30.8 ± 4.7                                                                       26.4 ± 4.7                                                                      24.9 ± 4.0                                (IV)   20 μg                                                                          32.6  13.9 ± 2.7                                                                      30.1 ± 4.8                                                                       22.4 ± 5.2                                                                      19.3 ± 4.3                                __________________________________________________________________________

Results are presented in Table 1, above, and in FIG. 1. Compounds (II)and (IV) produced significant reduction of intraocular pressure at doseswhich are marginal or ineffective for other prostaglandins in publishedclinical studies. Compound (II) was especially potent, producing almost50% reduction of intraocular pressure with just 5 μg of compound. Incontrast, Nakajima et al. (Graefe's Arch. Clin. Exp. Ophthalmol.,229:411-413 (1991)) reported that 50 μg of PGD₂ and 2.5 μg of BW245C (aPGD₂ analogue) reduce intraocular pressure in human eyes by 12% and 10%,respectively. Other studies (Woodward et al., Invest. Ophthalmol. Vis.Sci., 31:138-146 (1990)) reported for these reference compounds inrabbits describe a maximum IOP reduction of approximately 28% for 250 μgof PGD₂ and 22% for 25 μg of BW245C. These comparisons indicate theunexpected potency of compounds of the present invention in reducingintraocular pressure. No indications of inflammation were observedduring these studies.

The invention has been described by reference to certain preferredembodiments; however, it should be understood that it may be embodied inother specific forms or variations thereof without departing from itsspirit or essential characteristics. The embodiments described above aretherefore considered to be illustrative in all respects and notrestrictive, the scope of the invention being indicated by the appendedclaims rather than by the foregoing description.

What is claimed is:
 1. A method of treating glaucoma and ocularhypertension which comprises topically administering to the affected eyea therapeutically effective amount of a compound of formula: ##STR6##wherein: R₁ =CO₂ R₂, wherein R₂ =H, a cationic salt moiety, or anophthalmically acceptable ammonium moiety; or R₁ may also represent anophthalmically acceptable ester moiety;X=halogen; Y=CH₂ or O; R₃, R₄ canbe the same or different, and are selected from: free or functionallymodified hydroxy groups; and n=0 or
 1. 2. The method of claim 1,wherein: R₁ represents an ophthalmically acceptable ester moiety of theformula: CO₂ R₂, wherein R₂ =substituted or unsubstituted alkyl,cycloalkyl, (cycloalkyl)alkyl, aryl, or arylalkyl, and whereinsubstituents are selected from the group consisting of: alkyl, halogen,a free or functionally modified hydroxy group, or a free or functionallymodified thiol; and X=F or Cl in either configuration.
 3. The method ofclaim 2, wherein: R₂ =H, methyl, ethyl, n-propyl, isopropyl, t-butyl orbenzyl; X=Cl in the β (R) configuration; Y=O; R₃ and R₄ =OH; and n=1. 4.The method of claim 3, wherein: R₂ =isopropyl or t-butyl.
 5. The methodof claim 2, wherein: R₂ =H, methyl, ethyl, n-propyl, isopropyl, t-butyl,or benzyl; X=Cl in the β (R) configuration; Y=CH₂ ; R₃ and R₄ =OH; andn=1.
 6. The method of claim 5, wherein: R₂ =isopropyl.
 7. The method ofclaim 1, wherein between about 0.001 and about 1000 micrograms of acompound of formula (I) is administered.
 8. The method of claim 7,wherein between about 0.01 and about 100 micrograms of a compound offormula (I) is administered.
 9. The method of claim 8, wherein betweenabout 0.05 and about 50 micrograms of a compound of formula (I) isadministered.